iphone - How to force YouTube subtitles (closed captions) to appear by default even on iOS? -

i own youtube video, , typed subtitles it.

i've tagged yt:cc=on, , i've embedded iframe onto website using cc_load_policy=1&cc=1 (see docs).

when visit webpage using chrome on desktop, captions appear default, desired experience.

but when visit webpage using iphone (chrome on ios), captions not appear default. how can make captions appear default on ios?

(they available if click speech bubble icon, don't want users need know how that.)